let array=[1,2,3];
console.log([undefined].includes(),
			['undefined'].includes(),
			array.includes(2),
			array.includes(2,3),
			array.includes(2,2),
			array.includes(2,-5),
			array.includes(4),
			[].includes().call(object,1),
			[].includes().call(object,0));

let f = (x)=> x%2==0;
console.log(array.find(f),
			array.findIndex(f),
			array.filter(f));
